Field of the Inventions
Embodiments of the subject matter described herein relate generally to optical circuits which can include amplifiers and can be used as part of sensing apparatuses and for sensing methods such as Laser Imaging, Detection and Ranging (LIDAR) applications.
Description of the Related Art
Optical circuits are used in many different fields, including telecommunications and sensing technologies. In the telecommunications related technologies, light is primarily used as a carrier for digital communications. In such systems, the light remains contained within devices and circuitry which may be formed with integrated optical circuits, fiber optics, and other devices.
Optical circuits are also incorporated into certain types of sensing devices, such as velocimeters which can be used for detecting the velocity of a moving fluid, such as liquid within a pipe or atmospheric wind. Such sensing devices are known a laser doppler velocimeters (LDV). Such LDV devices have been incorporated into LIDAR systems, as well as other types of systems. LIDAR has been used for applications such as examination of surfaces of the earth. For example, LIDAR systems have been mounted in aircraft and flown over target during which light, in the form of a pulsed laser, is directed at surface features and the laser is used to measure ranges (variable distances) to the surfaces of the earth. The light pulses, combined with other data recorded by the airborne system, are used to generate precise, three dimensional information about the shape of the target area and its surface characteristics.
Recently, similar LIDAR systems have been developed for detecting wind velocities of wind approaching wind turbines, for optimizing operation of the wind turbines. In such systems, a pulsed laser light is discharged through a telescope, whereafter, the laser light strikes air molecules or particles suspended in the moving air, such as dust particles. Some of the laser light is reflected back to the telescope and is received by the LIDAR device. A sample of the original pulse laser light and some of the reflected laser light is processed to calculate a velocity of the wind, using known Doppler-based calculations.
While there are some similarities in the optical hardware used in telecommunications and LDV applications, energy magnitudes utilized in telecommunications hardware are orders of magnitude below the energy levels used for some LIDAR and environmental LDV applications. As such, some telecommunications hardware might be destroyed if they were used to transmit light at energy levels used in some environmental LDV applications.